FYI biofilms exist throughout the colon, they are normal and not something that needs to be eliminated!!!! It is only when pathogens form biofilms and take up residence on the colon wall that action needs to be taken to eliminate them which is difficult without harming the beneficial biofilms.
Glutamine will not heal Leaky Gut, it cannot because Leaky Gut is maintained by a Biofilm in order to provoke an immune reaction and increased histamine. The bacteria set up a feedback mechanism which benefits them.
You could consume Kilograms of Glutamine and it would just be a waste of money because it will not help while the biofilm exists. The body cannot heal itself while the biofilm prevents healing.